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Theory of Operation

Capacitance-based level instruments are based on a simple electronic component, the capacitor. A capacitor is an electronic component used for storing energy. It is important to note that the capacitance level controls do not store energy within the probe. Instead, they measure the amount of storable energy in units known as farads. However, in capacitance level measurements, there are relatively small amounts of capacitance and measurements are typically in picofarads (1 x 10-20 farads).

In order for a capacitor to function, the media between the plates must serve as an insulator. If a conductive material is placed between the plates, an electrical "short" will occur. As a result, the capacitor is comprised of a metal probe rod and outer shield (serving as the conductive plates) around the insulating, dielectric media.